为什么这个JavaScript调用不会破坏“相同的原始策略”？ [英] Why doesn't this JavaScript call break the "same origin policy"
问题描述
我正在使用jQuery显示外部JavaScript文件。原因是同源策略没有被破坏，因为它不是AJAX请求吗？
I'm displaying an external JavaScript file using jQuery. Is the reason "same origin policy" is not being broken because it is not an AJAX request?
小提琴代码：
HTML
HTML
<body>
<div id="toupdate">
<script type="text/javascript" charset="utf-8" src="http://static.polldaddy.com/p/6343621.js"></script>
</div>
</body>
jQuery
jQuery
$(document).ready(function() {
console.log('HTML is '+$('#toupdate').html());
});
推荐答案
哦，这里绝对没问题。您可以从任何地方引用javascript文件。例如，Google CDN提供了常用的js文件，例如你可以使用的jQuery：
Oh absolutely no problem here. You could reference javascript files from wherever you want. For example Google CDN provides common js files such as jQuery that you could use:
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.0/jquery.min.js"></script>
顺便说一下jQuery实现的方式 JSONP 有效。它使用javascript动态地将< script> 标记注入指向某个远程服务器端脚本的DOM：
By the way that's exactly how jQuery's implementation of JSONP works. It uses javascript to inject a <script> tag dynamically to the DOM pointing to some remote server side script:
<script src="//remotedomain.com/script?callback=abc"></script>
此远程脚本以 Content-Type：'application / x-响应javascript'回复标题和以下正文：
this remote script responds with a Content-Type: 'application/x-javascript' response header and the following body:
abc({"foo":"bar"})
在你的域名上你只需定义 abc 功能：
and on your domain you simply define the abc function:
<script type="text/javascript">
function abc(data) {
alert(data.foo);
}
</script>
然后你去：模拟跨域AJAX（我说模拟因为它不使用本机XHR对象但它实现了相同的效果。）
and there you go: a simulation of a cross domain AJAX (I say simulation because it is not using the native XHR object but it achieves the same effect).
现在您可以理解为什么jQuery的JSONP实现仅限于GET请求=>因为当您注入脚本标记时，浏览器只向其 src 属性发送GET请求。
Now you can understand why jQuery's JSONP implementation is limited to GET requests only => because when you inject a script tag, the browser sends only a GET request to its src attribute.
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